SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b7f1ee8d9023d2cfe848ed12027535ac0b4e19146e431233020d9714c8f8727' 
  AND token = 'snjdmGNvVhSsujMjPyBtorC5NUgTSEuDrbixwRhpwLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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