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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8751266a2a1ac9bf1179806e0d2a99623b11fbc0ad1251bb741d79bb4b4a7a4a' 
  AND token = 'YnMikzlPzXhWr0h9Z+lIR3rVt4x76g7n0fVuxCRMQuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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