SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab6708168eebe5aef59bd3252fedf74872072a6db2e0a836d3eb68cacccdfeff' 
  AND token = 'FplPvY01L+CNs1V/MzmtwDmTUSRbMipAo9YcPwcRWRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}