SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f4fb3791c864aed28ec0d5a456602a612abdf837fb6cf3c43d3966678a96ab7' 
  AND token = '9nnuNcg7WkUQvOSWhZfZBpmA7oV7Lw8YKUcp5jhMenw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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