SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb91ff4a7c12be7aaab78144d9e7e908d3c51c10492b26fe798d159f81695503' 
  AND token = 'AUNmt1fWSQYfgPmf6c6Me6I2pt53veHzsGzkPb8mGgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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