SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdf39e7a7ba903b84346dab2d53f2cff5fab29eafbe98e5cba2b65ebd97f1274' 
  AND token = '87BwvlfGR1KE53GNwx+SKQvfWRPQBNrUjHct4buqnGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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