SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f3693df8803774859176ae53feaaed67fdc41e2f0279da1b3fa70636d79f977' 
  AND token = 'tOwKEpPpkvGJJWnEOzEwZdxOEGRlxX8hpAtGLp3HVX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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