SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3531da11cf41682745094752519bac1891499da5410ba401d24d771ab0c8f01a' 
  AND token = '3NqXyzQA7Fq5eRnhRfCmY/QLXGTmx3wgIBNhUJ5L6Ls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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