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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '510f0c94cda07cd021f43fd5cd42beb003748370ca4511f53e238271011cd2cd' 
  AND token = 'Z9n/CcpUjh9qRqbRdfZiScjOjbJIMOykGhBpTK+LXGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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