SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c51743dd48db8247d2f0e2b4ceefe39869729092d22591bcaa7a27131a115679' 
  AND token = 'ooq9IAoKQ6sYDddp8NJhKCTCthxpNGc6hyC/1CrIPgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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