SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6bf87f3141ade55f2be1879eb8dbdf02e961cb941cfcc09fa71769138745df2' 
  AND token = 'zThmPPmQXYM1Y9+ZV9TK/Uu6BCCZkgZS9zszKj1nnL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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