SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b3dccfaef9534d4b01553d03f03f225213a0d476f300639ec8587601258e08fd' 
  AND token = 'KjOO+MdJfQIwitvYOtJ6yMI/G2n4UvbDLWG9ztihHJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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