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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9b04e5664b7ca9110763dd0ef3f315f1b646ee13d6425cc17131761091c0b21' 
  AND token = 'JxE6SY+qeqYEo8u2WXsty6Qf/Hk4SJPnc0ZgeMrgKnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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