SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18386143ac87f6b3634a5c9d89d1e61b2071c98d63210d2e55b6bd1a605e893a' 
  AND token = 'JfvcKf24uKar3Mv2AMPRYnuGw+NUZqBksfqk4rKqj08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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