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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '348b435e8eb3c36724384df734d2fa6104b526784b072a2d334e9cc29308b751' 
  AND token = 'x7gKNQyFjUQCarZ6vdw57JjQ1fcRcanMCwutgJn0l7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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