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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39974ccc0b247c2ae03dc4fe743d3ac2cbd77e322a48bd673ca7d9a3855ebe4' 
  AND token = 'zs3M+5n0ezWUlYCTU2dzJnZvm9bvSifMjX5r8u/vagQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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