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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b45f9e77dce7022121849e928bdcc5b3ddb1e009e70d06d9f3d35aa61f1d4a31' 
  AND token = 'j3lOQwpmpkImpC4mBRSAzxWu4LKMvjF4CsrelHYW0YE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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