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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '721bc5f0381c927c0fe7de40a393cecb4ead81d4c99cec15a148601e1ae41f99' 
  AND token = 'w1vK66/ay+rI3y6JEY8o/jsCvr1d/UFXR4UmTmZQ8XI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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