SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f9a18ff41b012a7d18d1146ce6534b942d7497a9f642108c9311bc727641a7' 
  AND token = 'i3EGl9YabkBZ60VNthaOn0hCd8lIUNOO4kgnQw8SABE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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