SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0cb4c792702d6fafca454f809c210a56fbd7236902db7fb1dfa32bb0b5573cf6' 
  AND token = 'kSpSim6NdnP2hS9w2iJvmeoye+BVKOGhKPGmoM3TTYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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