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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3d68977ddeee5d9d5ae81ec045c2d9abef8776e1e61b9275289d1b66644d052' 
  AND token = 'Gt324BIxRJ7flwzxPr5mu/Tx+p1l1pq9amyzJA4h2lU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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