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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1752ceca4be307d09cd60d022ec2944eb079403df1e2b9efa8b1024b3a8976ce' 
  AND token = 'dxNYIPE5f4NqRYtO91dQpwGsRyzvJbUCwBsbQz+r1fU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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