SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b53daf456840420700f14d1ff611ff9e15748ba9441cfe3a1147bcfe96f0c62a' 
  AND token = 'vsuh+xycNuWu3aL/c9aVvqXPImw9fB6prBllMVsww28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}