SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc91b601141877d1828f4b028501055ac9a98f855ac123983c62d33ae4ea3a28' 
  AND token = 'TEIeBeSkNZl1eiVvCOKE7M/fUM4deTdEq+nHS63nr8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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