SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ef390218f093d30cfa234eadb7d9a2f1c783a047aa8b71b78ee71ed3ac97dd0' 
  AND token = 'PZjkI6yeOaqsYn+l8pwsPrbmqKYVadXh1ojD+nRMkFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}