SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278c23ecc7cbf875172ce2786b19df3dcd602bbb0b01d670f289141fbdd67a17' 
  AND token = 'We8RP3kcUwtiFlsLJYGVlOVcCqEEOfsYFk9pT0FHGFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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