SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5f992766d1f8ca0e26ecfabd26fecb759dfe2b49281a23c9db7d9d4fcef644d' 
  AND token = 'zR51daeNYXvs2/DxRRz5eCfsWee9NbtH10yizN+Skhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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