SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecc3ebf00a4271321d046dd8e4cbb28084cfcbca76204b8463310cf41d943c90' 
  AND token = 'B9sL5iwYuJiBeCoDSYLgKC+UCm0AFBZCmkwvoDRj4o0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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